Turbodrill

ABSTRACT

A turbodrill for drilling wells having a turbine for the turbodrill shaft rotation together with a hydrodynamic braking unit, the stator and rotor blades of which extend in the same direction.

[451 Apr. 17, 1973 United States Patent 1191 Ioanesian et a1.

[ 1 TURBODRILL [76] Inventors: Jury Rolenovich Ioanesian, ulitsa 1/1966Ty1er.....

Bolshaya Dorogomilovskaya, 58, kv.

56; Rolen Arsenievich Ioannesian,

FOREIGN PATENTS OR APPLICATIONS naberezhnaya Tarasa Shevchenko, 1/2, kv.

h of Moscow, 690,613 7/1969Canada..................................415/55 U.S.S.R.

Primary Examiner-Henry F. Raduazo AttorneyHolman & Stern [22] Filed:Apr. 22, 1971 [21] App1.N0.: 136,525

ABSTRACT [52] U.S. Cl. ....,....,........4l5/l23, 415/502, 188/296 [51 Icl po 15/12, 031 3/10 2 1 1 A turbodrill for dri11ing wells having aturbine for the [58] Field ofSearch..............................188/290, 296; turbodrill Shaftrotation together with a hydrodynamic 415/123, 55, 502, 123, 502;175/107, 12 braking unit, the stator and rotor blades of which extend inthe same direction.

5 Claims, 13 Drawing Figures [56] References Cited UNITED STATES PATENTS1,161,116 11/1915 Ehrhart ..,.................,..........188/296PATENTEB APR 1 7 I973 SHEET 1 BF 4 TURBODRILL BACKGROUND OF THEINVENTION This invention relates to hydraulic bottom-hole motors fordrilling deep wells in the surface of the earth with the object ofobtaining oil, gas and other mineral resources, and more particularly toturbodrills.

PRIOR ART Known in the art is a turbodrill for drilling oil or gas wellscomprising a casing with fixed stators therein, the blades of whichdefine guiding channels through which a drilling fluid passes, and ashaft mounted in ball bearings and provided with fixed rotors, theblades of which have a direction opposite to that of a stator andthereby change the direction of fluid motion, due to which a rotor,constituting with a stator the stage of a turbodrill turbine, rotatesrelative to the stator.

In the course of operation of the turbodrill, the shaft rotates withhigh speed (900 rpm) driving the rock breaking tool, for example a rockbit, into rotation. The drilling of wells by rock bits with a high speedof rotation results in a decrease in the footage per bit, and in view ofthe fact that in deep drilling, a substantial percentage of time isconsumed by trips, the high speed drilling is economically inexpedient.

Turbodrill designs are known in which the r.p.m. is reduced by means ofa mechanical reducer. However, these turbodrills are very complicated tomanufacture, and are unreliable in operation because of the heavydutyconditions of a reducer.

Also known are turbodrill designs in which a decrease in rotationalspeed of the shaft is attained by adjusting the flow rate of a fluidwhich is supplied to the turbodrill. Among these are the turbodrillsprovided with reducing valves and flow rate ejector-multipliers whicheffect a decrease in rotational speed of the shaft to that in rotarydrilling. However, turbodrills with reducing valves and flow rateejector-multipliers are also complicated to manufacture.

A principal object of the present invention is to provide a turbodrillof a simple design and which ensures a high reliability of a drillingbit operation at the rpm characteristic of rotary drilling.

SUMMARY OF THE INVENTION The turbodrill of the present inventioncomprises a casing with immovably fixed stators, the blades of whichdefine guiding channels through which a drilling fluid passes and ashaft mounted in a ball bearing means provided with immovably fixedrotors, the blades of which have a direction opposite to that of thestator blades and thereby change the direction of fluid motion, due towhich a rotor constituting with a stator, the stage of a turbodrillturbine, rotates as related to a stator, and a means for reducing theshaft rotational speed. According to the invention, the means forreducing the rotational speed of a shaft is constituted by furtherstators fixed in the turbodrill casing and further rotors secured to theshaft, with both components constituting hydrodynamic braking stages inwhich the blades of the further stator and further rotor have, mainly,one and the same direction.

It is expedient that the stator and rotor blades, reducing the shaftrotational speed, be disposed at the same angles to a plane normal tothe turbodrill shaft axis.

It is also expedient that the stator and rotor blades reducing the shaftrotational speed be of variable height, which increases proportionallyto a radial distance of a blade section from the turbodrill shaft axis.This provides for the drilling fluid flow without surging shock throughthe stator and rotor blades and thereby reduces pressure losses acrossthe braked turbodrill and aids in reducing head losses when theturbodrill is idle. The stator and rotor blades reducing the shaftrotational speed may also be of constant height. These blades have theadvantage of being simple to manufacture.

The stator and rotor blades reducing the rotational speed of the shaftare preferably of a streamlined shape, formed by mold curves, with theirmiddle lines being disposed at the same angle to a plane normal to theturbodrill shaft axis. This provides a decrease of hydraulic losses inthe hydrodynamic braking stages.

According to this invention, a turbodrill of a simple design isdeveloped, which provides the high reliability of a drilling bitoperation at the rpm characteristic of rotary drilling.

The invention will be further described with reference to an embodimentshown in the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionthrough a turbodrill according to the invention;

FIG. 2 is a fragmentary sectional view of a turbine stage; I

FIG. 3 is a fragmentary cross-sectional view of the stator and rotorblading of a turbine stage;

FIG. 4 is a fragmentary sectional view of a hydrodynamic braking stage;

FIG. 5 is a fragmentary cross-sectional view of the stator and rotorblading of a hydrodynamic braking stage;

FIG. 6 is a view illustrating an angle at which the stator and rotorblades of a turbodrill hydrodynamic braking stage, according to theinvention, are mounted on the plane; at this angle the hydrodynamicbraking stages act not only as a brake, but also as a pressureregulator;

FIG. 7 is a view illustrating the same angle at which thehydrodynamicstages offer the greatest braking effect;

FIG. 8 is a view illustrating the same angle at which the hydraulicresistance increases more intensively from braking regime to idlingregime than at above said angles;

FIG. 9 is a diagrammatic view of turbine curves of the turbodrill withhydrodynamic braking stages and with the setting angle of bladesaccording to FIG. 6;

FIG. 10 is a diagrammatic view with the setting angle of bladesaccording to FIG. 7;

FIG. 11 is a diagrammatic view with the setting angle of bladesaccording to FIG. 8;

FIG. 12 is a longitudinal section of a hydrodynamic braking stage withblades the height of which increases proportionally to a radial distance'of a blade section from the turbodrill shaft axis;

FIG. 13 is a cross-sectional view of a shaped rotor and stator blade ofa hydrodynamic braking stage, the

blade being of streamlined shape formed by mold curves.

DETAILED DESCRIPTION OF THE INVENTION The turbodrill shown in FIG. 1, inits upper part has a turbine 1 comprising stages 2, with each beingconstituted by a stator 4 (FIG. 2) fixed in casing 3 (FIG. 1,2,4), withblades 5 (FIG. 3) thereof defining guiding channels 6, through which adrilling fluid passes, and a rotor 8 (FIG. 2) secured to a turbodrillshaft 7, with blades 9 thereof having a direction opposite to that ofthe blades 5 thereby changing the direction of fluid motion. As a resultthereof, the rotor 8 rotates as related to the stator 4 and transmitsthe torque of rotation to the turbodrill shaft 7.

In the bottom part of the turbodrill, further stators 10 (FIG. 4) fixedin the casing 3 have blades 11 (FIG. 5) and further rotors 12 (FIG. 4)secured to the shaft 7 have the blades 13 (FIG. 5) with the stators 10and rotors 12 being disposed at the same angles to a plane normal to theaxis of the turbodrill shaft 7.

The blades 13 of the rotor 12 are represented as if they are anextension of the blades 11 of the stator 10 and vice versa. The stator10 and rotor 12 constitute a stage 14, and stages form a hydrodynamicbraking unit 15, which reduces the speed of rotation of the turbodrillshaft 7.

With a braked turbodrill shaft, a drilling fluid passes freely throughthe stator and rotor blades of the hydrodynamic braking stages. In thiscase, a minimum pump head is consumed, and hydraulic resistance inrotors and stators is due to the surface irregularities of the channelsand inaccuracy of the blade shape.

As the rotational speed of a turbodrill rotor increases, which may becaused by a decrease of bit weight or by a reduction of torque loadapplied to a turbodrill rotor, an eddy zone is developed behind theblading. The rotor blades of the hydrodynamic braking stages startoperating as a rotor of an axial pump, taking up a part of the rotorpower and building up an effective fluid head which assists counteractsthe mud pumps in forcing the fluid through the operating turbine of theturbodrill.

The rotor and stator blades of a hydrodynamic braking stage are shown inFIGS. 6, 7, 8. The stator and rotor blades of each stage have or extendin the same direction and are disposed at the same angles (a, a 0: Thecourse of the drilling fluid motion is shown by solid arrows, and thedirection of rotor motion, by dashed arrows.

The indicated angles distinguish three preferable variants of bladessetting in rotors and stators of hydrodynamic braking stages, each ofwhich provides for a specific characteristic of the turbodrill.

The blades setting in rotors and stators of hydrodynamic braking stagesaccording to the first variant (FIG. 6) is expedient to use withturbines, the hydraulic resistance of which reduces as the rpm isdecreased.

The initial characteristic curve of the turbodrill with such a turbineand the characteristic curve which is obtained as a result of setting uphydrodynamic braking stages with blades shown in FIG. 6, is shown inFIG. 9 in which n, is the idling rpm of the turbodrill shaft,

N is the operational rpm of the turbodrill shaft,

M, is the braking torque of the turbodrill,

M is the operational torque of the turbodrill,

P is the braking pressure drop across the turbodrill,

P is the operational pressure drop across the turbodrill,

I the torque line M/M, flit/n for turbodrills without hydrodynamicbraking stages,

II the head loss line P/Pp =f(n/n for a turbodrill without hydrodynamicbraking stages;

1,, the torque line M/M =f(n/n,) for a turbodrill with K number ofhydrodynamic braking stages,

1,, the same for K number of hydrodynamic braking stages, where K K 1],,the head loss line P/P =f(n/n for a turbodrill with K, number of brakingstages 11,, the same for X number of hydrodynamic braking stages, whereK K As illustrated in FIG. 9, in this case the hydrodynamic brakingstages function not only as a brake impeding the turbodrill speeding up,but also as a pressure regulator which prevents the pressure frombuilding up beyond an allowable value. By setting up a sufficient numberof hydrodynamic braking stages, it is possible not only to decrease theidling rpm of the turbodrill shaft, but also narrow the operational rpmrange.

With these hydrodynamic braking stages being used, the pressure lossacross the turbodrill will be minimum.

In some cases, it is expedient to use the hydrodynamic braking stageswith vertical rotor and stator blades, the second variant (FIG. 7) andexperience has shown that such blades have maximum braking capacity. Thecharacteristic curve of a turbodrill with such hydrodynamic brakingstages is shown in FIG. 10. The designations in FIG. 10 correspond tothe designations in FIG. 9.

Such hydrodynamic braking stages increase the hydrauiic resistancefactor of the turbodrill as a whole and particularly as compared to thebraking stages made in accordance with the first variant (FIG. 6).

Vertical blades cannot be used as a head loss regulator in theturbodrill, but they are very simple and lowpriced to manufacture:therefore they may find wide industrial use.

For a low number of turbodrill shaft operational rpm (in the order oftens rpm) to be obtained, the third variant of the hydrodynamic brakingstages embodiment (FIG. 8) holds much promise.

In this case, with the turbodrill rotor being immovable, hydrodynamicbraking stages, as well as in the first variant (FIG. 6), hardly resultin an increase of pressure loss across the turbodrill, that is increaseslightly the total pressure drop across the braked turbodrill as awhole.

However as the rotational speed of a turbodrill shaft increases, theturbodrill starts to operate more and more as an axial pump producingcounterpressure for a mam pump.

The hydraulic resistance factor of a turbodrill with a turbine, thehydraulic resistance of which decreases with a reduction of rotationalspeed of a turbodrill shaft increases the most intensively with anincrease in speedtipliers, as well as in turbodrills with reducingvalves, that is in all turbodrills in which the flow rate of a drillingfluid supplied to the turbine depends on the tur bodrill operatingconditions, the minimum operating rpm may be obtained. With the bladesof hydrodynamic braking stages being inclined to a plane normal to theturbodrill axis (FIG. 6 and 8), the drilling fluid flow without surgingshock through the stator and rotor blades is of great importance inreducing the hydraulic resistance factor of a braked turbodrill as wellas the rate of head loss decrease with the turbodrill idle rotation,which is possible only when the outlet blades of the rotor and statorare directed along the radius. The last-mentioned condition isimpossible with inclined blades being made of a constant axial heightindependently of the distance, at which the blades section is disposedfrom the turbodrill axis.

Therefore, for the head loss with a braked turbodrill to be reduced, theblades of the hydrodynamic braking stages according to the first andthird variants (FIGS. 6 and 8) should be made of variable axial heightalong the radius, as shown in FIG. 12. In cases in which the axialheight H of a blade increases proportionally to the distance of theblade section from the turbodrill axis, it is possible to fulfill twomost important conditions, that is: the inclination of the blade axis toa plane normal to the turbodrill axis is the same along its full heightand, in addition, the input and output edges of the blade are directedalong the radius, that is the projections of the input and output bladeedges on a plane normal to the turbodrill axis coincide with the radiusdirections.

To facilitate the hydrodynamic braking stages blades casting, they maybe given a streamlined shaped, formed by mold curves. The shape of sucha blade is shown in FIG. 13. In this case, the inclination of the bladeto a plane normal to the turbodrill shaft axis, is determined by theinclination of the middle line m," and the projections of input a" andoutput b" blade edges on a plane normal to the turbodrill shaft axiscoincide with the radius directions.

We claim:

l. A turbodrill for drilling wells including: a casing; stators securedto said casing, the stators having blades, the blades of the statorsdefining guiding channels through which a drilling fluid passes; ashaft; ball bearing means on which said shaft is mounted; rotors securedto said shaft, said rotors having blades, the

blades of the rotors having a direction opposite to that of the bladesof said stator thereby changing the direction of fluid motion; due towhich said rotor constituting with said stator a stage of a turbodrillturbine, rotates as related to said stator; and means for reducing therotational speed of said shaft defined by further stators fixed in saidturbodrill casing and further rotors secured to said shaft providinghydrodynamic braking stages said further stators and rotors havingblades, the blades of said further rotors and further stators extendingin the same direction, with the angles of the inlet and outlet of allblades being the same.

2. A turbodrill for drilling wells including: a casing; stators securedto said casing, the stators having blades, the blades of the statorsdefining guiding channels through which a drilling fluid passes; ashaft; ball hearing means on which said shaft is mounted; rotors securedto said shaft, said rotors having blades, the blades of the rotorshaving a direction opposite to that of the blades of said stator therebychanging the direction of fluid motion; due to which said rotorconstituting with said stator a stage of a turbodrill turbine, rotatesas related to said stator; and means for reducing the rotational speedof said shaft defined by further stators fixed in said turbodrill casingand further rotors secured to said shaft providing hydrodynamic brakingstages in which the blades of said further rotors and further statorsextend mainly in the same direction, with the blades of said stators androtors reducing the rotational speed of said shaft being disposed at thesame angles to a plane, normal to the axis of said turbodrill shaft.

3. The turbodrill as claimed in claim 1, in which the blades of saidstators and rotors, reducing the rotational speed of said shaft, are ofvariable height increasing proportionally to a radial distance of ablade section from the axis of said turbodrill shaft.

4. The turbodrill as claimed in claim 1, which the blades of saidstators and rotors, reducing the rotational speed of said shaft, are ofa constant height.

5. The turbodrill as claimed in claim 1, in which the blades of saidstators and rotors, reducing the rotational speed of said shaft, are ofa streamlined shape, defined by mold curves, and their middle linesbeing disposed at the same angle to a plane normal to the axis of saidturbodrill shaft.

1. A turbodrill for drilling wells including: a casing; stators securedto said casing, the stators having blades, the blades of the statorsdefining guiding channels through which a drilling fluid passes; ashaft; ball bearing means on which said shaft is mounted; rotors securedto said shaft, said rotors having blades, the blades of the rotorshaving a direction opposite to that of the blades of said stator therebychanging the direction of fluid motion; due to which said rotorconstituting with said stator a stage of a turbodrill turbine, rotatesas related to said stator; and means for reducing the rotational speedof said shaft defined by further stators fixed in said turbodrill casingand further rotors secured to said shaft providing hydrodynamic brakingstages said further stators and rotors having blades, the blades of saidfurther rotors and further stators extending in the same direction, withthe angles of the inlet and outlet of all blades being the same.
 2. Aturbodrill for drilling wells including: a casing; stators secured tosaid casing, the stators having blades, the blades of the statorsdefining guiding channels through which a drilling fluid passes; ashaft; ball bearing means on which said shaft is mounted; rotors securedto said shaft, said rotors having blades, the blades of the rotorshaving a direction opposite to that of the blades of said stator therebychanging the direction of fluid motion; due to which said rotorconstituting with said stator a stage of a turbodrill turbine, rotatesas related to said stator; and means for reducing the rotational speedof said shaft defined by further stators fixed in said turbodrill casingand further rotors secured to said shaft providing hydrodynamic brakingstages in which the blades of said further rotors and further statorsextend mainly in the same direction, with the blades of said stators androtors reducing the rotational speed of said shaft being disposed at thesame angles to a plane, normal to the axis of said turbodrill shaft. 3.The turbodrill as claimed in claim 1, in which the blades of saidstators and rotors, reducing the rotational speed of said shaft, are ofvariable height increasing proportionally to a radial distance of ablade section from the axis of said turbodrill shaft.
 4. The turbodrillas claimed in claim 1, which the blades of said stators and rotors,reducing the rotational speed of said shaft, are of a constant height.5. The turbodrill as claimed in claim 1, in which the blades of saidstators and rotors, reducing the rotational speed of said shaft, are ofa streamlined shape, defined by mold curves, and their middle linesbeing disposed at the same angle to a plane normal to the axis of saidturbodrill shaft.